Antimicrobial activity of secondary metabolites isolated from Centaurea spruneri Boiss.& Heldr.

Abstract

Two coumarins, scopoletin (1) and isoscopoletin (2), two simple phenolic acids, protocatechuic acid (3) and isovanillic acid (4) and one flavonoid, eriodictyol (5) were isolated from the aerial parts of Centaurea spruneri. The structure of the compounds was established by spectroscopic methods. The in vitro antimicrobial activity of the isolated compounds was tested against eight bacteria and eight fungal species, using a microdilution method. All compounds tested showed moderate antibacterial and antifungal activities. Their minimum inhibitory concentrations were in the range 0.655 - 2.38 ?mol ml-1 and their minimal bactericidal concentrations ranged from 0.694 to 4.15 ?mol ml-1 against the tested bacterial species. All compounds showed fungistatic activity at 0.259 - 2.38 ?mol ml-1 and fungicidal at 0.69 - 2.6 ?mol ml-1 against all fungi tested.